The present invention relates to printheads with multiple printhead dies and, more specifically, to temperature control among the multiple printhead dies to improve print quality.
Several types of printing devices are known in the art and they include laser, dot matrix, mechanical actuated ink jet and thermal actuated ink jet printers and the like. The present invention is particularly applicable to ink jet printers and, more specifically, to thermal actuated ink jet printers. Nonetheless, it should be recognized that the effects of temperature on ink and print quality may be an issue in all types of printers (because of the coefficient of expansion of ink and other materials, among other reasons) and thus, the present invention is applicable to all printers.
Ink jet printheads are known that include a semiconductive substrate or xe2x80x9cdiexe2x80x9d on which are formed a plurality of firing chambers. Ink and control signals are provided to the firing chambers for controlled expulsion of ink. In order to achieve faster printing rates, the present invention contemplates providing a plurality of these dies in a side by side arrangement or the like (thereby creating a larger ink expulsion area), and such an arrangement is termed an array or module (hereinafter referred to as an xe2x80x9carrayxe2x80x9d).
When multiple dies are placed side by side to form a printhead array, however, print quality issues can arise. A principal concern stems from the performance of two neighboring dies that are operating at different temperatures. The concern usually manifests itself as a sudden change in image intensity at the interface between the dies. The change in image intensity is caused by different sized ink drops being expelled by the neighboring die because ink drop volume varies with die temperature. Thus, a need exists to provide a printhead array in which the printhead dies or the like are maintained at a more uniform temperature and thus produce ink drops of more uniform volume.
Accordingly, it is an object of the present invention to provide a multiple printhead arrangement that creates ink drops having an approximately uniform volume.
It is another object of the present invention to provide a multiple printhead arrangement in which the operating temperature of each printhead is controlled.
It is also an object of the present invention to provide a multiple printhead arrangement in which each of the printheads operate at approximately the same temperature.
These and related objects of the present invention are achieved by use of a multiple printhead apparatus with temperature control and method as described herein.